Due to potential widespread effects of the proposed half-cent transportation tax, Miami-Dade County’s 3,500-member Sierra Club will Monday consider backing the November ballot issue.

The environmental group’s local chapter opposed a similar transportation tax referendum three years ago because they thought it had poorly designed funding and land-usage proposals, group leaders said.

Sierra Club board member Lee Swerdlin said the group, though not eager to jump on political bandwagons, may now consider backing the referendum on its urban environmental benefits, which include creating transportation alternatives for the suburbs.

"If we’re going to take a position we need to get the facts straight on how the proposal would affect quality of life from a land-use and environmental perspective," said local club President Stuart Reed. "But from what I understand this proposal is vastly different than what came last time around."

The initiative, dubbed "The People’s Transportation Plan " and spearheaded by county Mayor Alex Penelas’ administration, calls for a half-cent sales surtax to collect about $150 million a year for transportation improvements. It is also the first to include a citizen oversight board to audit the implementation of surtax-funded projects.

If approved by county voters in November, transportation planners would begin phasing in portions of a 30-year plan to double the bus fleet, add 90 miles of rail lines – including the Bay Link between downtown Miami and Miami Beach – and overhaul major roads and highways in the county.

Mr. Swerdlin said the county desperately needs transit alternatives to help decrease car traffic and pollution.

"New cities like Miami and L.A. were modeled after the automobile, which has lead to traffic congestion, pollution and urban sprawl," said Mr. Swerdlin, who also sits on the county’s Citizens’ Transportation Advisory Committee. "Our urban model based on the automobile is the worst decision ever made. Miami is a classical example of doing everything wrong."

Mr. Reed said electric-based alternatives such as some light-rail proposals under development create less pollution than combustion engines.

On a separate front, the Miami Business Forum, a group of about 40 local executives, plan to discuss whether or not to support the proposal Sept. 10.

Mario Artecona, forum executive director, said he thinks the initiative has a "solid system of checks and balances" to ensure money is spent appropriately.

"To get a tax passed in this county you have to tell people that it’s not just a blank check to the county commission. That’s too great a leap of faith to ask the voters."

And, the Greater Miami Chamber of Commerce has called for dedicated transportation funding since 1972, according to Barry Johnson, executive committee member overseeing governmental affairs.